Nanoscale dynamic and long-range effects under cascade-forming irradiation

Abstract

Classical radiation physics describes well a number of known phenomena in irradiating metals and alloys (radiation embrittlement, swelling, radiation creep) on the basis of relatively slow processes of thermo- and radiation-enhanced diffusion. Mechanisms based on the description of the defect migration processes cannot, however, explain the “small-dose effect” under neutron as well as low-dose “long-range effect” under ~(104–k · 105) eV (1 ≤ k ≲ 3) ion irradiation.11Relatively cheap and simple accelerators (sources) of ions of the indicated energy range, generating high-current ion beams of large cross section, are increasingly used to modify the properties of materials. They can easily be included in the technological processes, in contrast to high-energy accelerating equipment. This paper takes a brief look at the model taking into account the explosive energy release in the regions of the dense cascades of atomic displacements (formation of thermal spikes) and the emission of powerful post-cascade solitary waves that are able initiate structural-and-phase transformations at their front in metastable media, theoretically, at unlimited distances. In practice observed distances of accelerated (104–k · 105) eV ion beams action (in continuous mode) are sometimes more than a few tens/hundreds of micrometers (at Rp < 1 μm; Rp is the projected ion range) and up to 1–10 mm as it was shown in the last experiments. It should be noted that the energies of recoil atoms generated by reactor neutrons and fission fragments also partly belong to the above-mentioned energy range, but the consideration of post-cascade effects for these types of irradiation is beyond the scope of the survey.